1. Field of the Invention
The present invention relates to an imaging apparatus in which pixels each having a switching element, such as a thin-film transistor (TFT), and a conversion element for converting a light signal into an electric signal are arranged in a two-dimensional fashion, and to a radiation imaging apparatus utilizing the imaging apparatus and a scintillator. Moreover, the present invention relates to a radiation imaging apparatus utilizing conversion elements for converting radiations into electric signals. Still moreover, the present invention relates to methods for manufacturing the imaging apparatus and the radiation imaging apparatus.
2. Description of the Related Art
In recent years, enlargement of a TFT matrix panel, in which TFTs as switching elements are formed on an insulating substrate, has rapidly been promoted. In addition, techniques for area sensors utilizing switching elements and sensor elements have also been put to practical use. In an area sensor utilized as an imaging apparatus, pixels, in each of which a TFT and a conversion element that serves as a photoelectric conversion element make a pair, are arranged in a matrix form. In the case where an area sensor is utilized as a radiation imaging apparatus, a scintillator, which converts a radiation into light, such as visible light or infrared light, that falls within a wavelength bandwidth that can be sensed by a photoelectric conversion element, is arranged on the area sensor as an imaging apparatus; light from the scintillator is photoelectrically converted by a conversion element that serves as a photoelectric conversion element. Area sensors as radiation imaging apparatuses include an area sensor utilizing TFTs and conversion elements made of a semiconductor conversion material that converts a radiation directly into an electric signal.
With regard to the foregoing imaging apparatus and the radiation imaging apparatus, enhancement of the sensitivity of a conversion element and the driving speed of a switching element have also been promoted. For the purpose of achieving the high sensitivity and the high speed, a laminate-structure pixel in which a conversion element is arranged on a switching element or a wiring connected to a switching element is desirable.
An imaging apparatus having pixels of the foregoing laminated structure is described in Japanese Patent Application Laid-Open No. H11-097660.
To date, in a laminate-structure imaging apparatus or a laminate-structure radiation imaging apparatus in which, after TFTs are formed, conversion elements are formed, proposals have been made in which, in the case where a defect is caused in a pixel, the defective pixel is electrically isolated by means of a laser beam so as to be removed without affecting the peripheral pixels.
In an imaging apparatus or a radiation imaging apparatus that is disclosed, as a conventional example, in the specification of US Patent Publication No. 2004-159794 (Japanese Patent Application Laid-Open No. 2004-179645), semiconductor conversion elements are arranged on switching elements. In addition, it is described that the imaging apparatus or the radiation imaging apparatus is formed in such a way that part of an electrode of the conversion element within a region onto which a laser beam is irradiated is removed.
Additionally, the lower electrode of the conversion element is provided with an opening on the corresponding TFT. As a result, in the case where a defect is caused in a conversion element of a pixel, by irradiating a laser beam through the corresponding opening onto the TFT, thereby electrically isolating the TFT from the conversion element.
In the imaging apparatus or the radiation imaging apparatus that is disclosed in US Patent Publication No. 2004-159794 (Japanese Patent Application Laid-Open No. 2004-179645), a lower electrode and a second semiconductor layer that configure a semiconductor conversion element are arranged in such a way as to avoid the top side of the corresponding TFT. Since the TFT is covered with neither the lower electrode nor the second semiconductor layer, visibility for the TFT portion is enhanced when the remove is carried out, whereby alignment can be made without mixing up a portion to be removed with a wrong portion.